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1. FRONTAL LOBE
BY DR.DHARANEEDHAR
PG – DEPT. OF PSYCHIATRY

2. TOPICS
 INTRODUCTION
 NEUROANATOMY
 NEUROPHYSIOLOGY
 CLINICAL SIGNIFICANCE
 PSYCHIATRIC SIGNIFICANCE

3. INTRODUCTION
 The frontal lobe is a largest lobe, located anterior to the
central sulcus which separates from ‘parietal lobe’ and
above to posterior ramus lateral (sylvian)sulcus which
separates from ‘temporal lobe’
 It is developed from Telencephalon of forebrain after 3rd
week & reaches to full maturity by late 20’s of age.

4.  Primitive reflexes – grasp & grope reflexes are
associated with frontal lobe
 The frontal lobe is involved in emotions, language, motor
tasks, reasoning, judgment, abstract thinking, creativity,
and maintaining social appropriateness.
BLOOD SUPPLY- by two branches of the internal carotid
artery: the anterior cerebral arteries and the middle
cerebral arteries.
 Collateral supply by anterior communicating artery

5. NEUROANATOMY

6. PARTS OF LOBE
 SULCI & GYRI
1. Prefrontal sulcus – precentral gyrus
2. Superoir & inferior frontal sulci – superior, middle,
inferior frontal gyri
3. Rami of Lateral sulcus- pars orbitalis, pars
triangularis, pars opercularis

7. FUNCTIONAL AREAS :-
 Primary motor area (area 4 of brodmann)
 Premotor area (area 6 of brodmann)
 Supplementary motor area
 Frontal eye field (area 8 of brodmann)
 Motor speech area of BROCA (44 & 45)
 Prefrontal area
1. Dorsolateral prefrontal cortex (DLPFC)
2. Ventrolateral prefrontal cortex (VLPFC)
3. Orbitofrontal cortex (OFC)

9. NEUROPHSYIOLOGY

10. PRIMARY MOTOR CORTEX (BA 4):
 ~ 40% Pyramidal fibres (corticospinal tract)
 Motor Homunculus- fingers, lips, and tongue are
represented by large regions of cortex, whereas the toes
are represented by a relatively small region , this size
corresponds to degree of motor control.
 The primary motor cortex along the midline controls the
body below the waist. The primary motor cortex located
on the lateral surface of the brain controls the muscles of
the body found above the waist

12. LESION :
 paralysis of contralateral musculature. The affected
muscles are flaccid at first then reflexes become brisk
and the muscles exhibit spasticity.
 Gross movement control reappears after several weeks,
but fine movements are usually lost permanently.
BED SIDE EVALUATION:-
 HAND GRIP – for motor strength
 FINGER TAPPING

13. PRE-MOTOR CORTEX (BA 6)
 30% corticospinal tract fibres
 Programming of motor activity
 Axons descend from the premotor cortex through the
internal capsule to the reticular formation of the
brainstem where they influence the reticulospinal tracts
which function in support of body posture and
locomotion through control of axial and proximal limb
musculature.
 Premotor areas appear to be involved in the generation
of a motor sequence from memory that requires precise
timing and appear to play an important role in sensory
conditioned motor learning.

14. LESIONS
 Deficits in visually guided movements is seen
 Unilateral lesions of the premotor cortex result in
moderate weakness of contralateral shoulder and
pelvic muscles & grasping movements.
BED SIDE EVALUATION
1. Touch each finger to thumb in rapid succession
2. Apraxia – to blow a kiss , to draw a cube

15.  MIRROR NEURONS : produces empathy, sympathy,
and other aspects of emotional feeling which are
important for developing appropriate social skills.

16. SUPPLEMENTARY MOTOR AREA AND
SUPPLEMENTARY MOTOR COMPLEX
 Two major subdivisions of SMC
1. Pre- supplementary motor area (pre-SMA) -
performing unfamiliar motor tasks (“attention to
intention”) .
2. SMA proper was activated when sequential
movements were elicited.
 During a new motor (learning) sequence of actions
SMC gets activated where a familiar motor sequence
must be inhibited.

17.  The SMA may be involved in procedural memory –the
process responsible for acquisition and recall of motor
programs (e.g., how a novice learns to grip and swing a
golf club).
LESIONS
 Motor neglect is characterized by utilization of the
contralesional side
 Recovery may complete in several years but mistakes
may be observed in repeated complex movements of the
hand.
BED SIDE EVALUATION
 Alternating hand sequences shows the hand hesitating to
reverse movement

18. FRONTAL EYE FIELD
 Involves in Voluntary eye movements.
FRONTAL
EYE FIELD
SUPERIOR
COLLICULUS
CAUDATE
NUCLEUS
Paramedian
Pontine
Reticular
Formation
(Lateral Gaze)
MIDBRAIN
(riMLF)
VERTICAL
GAZE

19.  CORTEX-GENERATED EYE MOVEMENTS :
1. The saccade is a fast eye movement that functions to
reset eye position onto a new target. Visual signals
from the retina to the cortex are inhibited during a
saccade.
2. The pursuit eye movement - occur once the target of
interest is positioned on the fovea & allows the eye to
track a moving object.

20.  The frontal cortex acts as the executive and selects one
target out of all the available visual targets. It then
generates and triggers a saccade to move the eyes onto
the selected target.
 A relationship between the function of the DLPFC and the
frontal eye field in the voluntary control of eye movement,
is one of the highest orders of cognitive processing in
primates including humans.
LESION
 Eye tracking dysfunction (ETD) appears to be a
genetically determined trait marker of schizophrenia.

21.  It is hypothesized that antisaccade task errors &
ETD represent dysfunction in the DLPFC.
 Antisaccade errors in schizophrenia represent
impairments in working memory, including elements
of inhibition.
BED SIDE TEST-
 Following finger movement
 Movement of eyes left to right , up & down.

22. BROCA’S SPEECH AREA BA 44 AND BA 45
 This region is specialized on the dominant side of the
cortex for the production of speech. The major input is
from Wernicke’s area .
 Broca’s on the nondominant cortex is responsible for the
emotional/melodic component of speech (prosody)
 It is activated during the production of both overt and
covert speech as well as when an individual imitates
another person’s speech
 Verbal hallucinations experienced by patients with
schizophrenia involves this area.
 It is also involved in word retrieval as well as in verbal
fluency.
 Depression often accompanies Broca’s and other
nonfluent aphasia

23. LESION:
 Impairment in verbal fluency is seen in patients
 A lesion on dominant side results in an inability to
produce speech (motor or expressive aphasia).
 The patient retains the ability to understand the written
and spoken word.
 A lesion on the non-dominant side results in expressive
aprosodia in which the patient is unable to effectively
modulate speech (i.e., speech becomes monotone
without facial expressions).

24. BED SIDE EVALUATION :
 Speech sample
 Say as many words beginning with ‘s’ in the next 30
seconds

25. PREFRONTAL CORTEX
 Prefrontal areas are involved in storage and retrieval related to
sequential and temporal aspects of planning (“organ of
creativity” )
 It is divided in to
1. Dorsolateral Region
2. Orbital (Inferior) Region
3. Medial region
 All three regions receive fibers from the MD thalamic nucleus,
which relays information from the temporal cortex, the pyriform
cortex, and the amygdala.
 The dorsolateral region functions in the cognitive sphere
dealing with perception, memory and motor planning.
 The inhibition of glutamatergic transmission in the prefrontal
lobes correlates with cognitive dysfunction seen in patients
with schizophrenia.

26. LESION
 Bilateral damage to the prefrontal lobes can produce
severe behavioral changes like - apathetic and exhibit
disinhibition of impulsive behavior, appear unconcerned
(abulia) and exhibit slowness and lack of spontaneity in
speech and slowness in thought and in emotional
expression.
 Prefrontal syndrome called the environmental
dependency syndrome (EDS) a disorder in personal
autonomy
 Orbitofrontal damage alone or combined with temporal
pole damage can result in complex behavioral changes.
 Extensive orbital cortex damage blunts emotional
reactions, and the patient may sit quietly and silently.
 Mothers with orbital lesions neglect or beat their children
without provocation

27. DORSOLATERAL PREFRONTAL CORTEX
 The DLPFC is heavily involved in working memory which
is the act of bringing to mind and processing limited
amounts of information (eg- reading and recalling a
telephone number or solving a math problem “in your
head”)
 Two components of working memory are seen
1. The short-term component operates on the order of
seconds.
2. The second component executive processing and
operates on information retrieved from storage.
 Symbolic representations retrieved from long-term
memory as well as from current sensory cues are
“sketched out” in the DLPFC as a function of working
memory.

28. LESIONS
 Abnormalities in complex psychological functions that are
classified as executive function deficits- planning,
feedback, learning, sequencing, establishing,
maintaining, and changing a set behavior.
 The ability to organize events in temporal sequence is
most affected.
 Perseveration, stimulus bound behavior and echopraxia
 General disinterest, apathy, shortened attention span,
lack of emotional reactivity, and difficulty in attending to
relevant stimuli
 A reduction in verbal fluency may be seen

29. BED SIDE EVALUATION:
 Digit span
 The Wisconsin Card Sorting Test is valuable in
evaluating the status of the dorsolateral area.
 COWAT- controlled oral word association test-
asking patient to speak as many words as possible
in 1min with letters starting from F,S,A
 Alternating hand sequence

30. VENTROLATERAL PREFRONTAL CORTEX
 BA 44, BA 45 and the lateral aspect of BA 47 are
involved.
 The left VLPFC and is involved with semantic
processing and is better understood.
 The right VLPFC is linked to emotional aspects of
faces.
 VLPFC may be involved in the manifestation of
anxiety symptoms and through connections with the
amygdala may regulate responses to anxiety-
provoking stimuli, thereby reducing the severity of
symptoms

31. ORBITOFRONTAL CORTEX
 Includes- BA 11, BA 12, and the medial portion of BA 47.
 It receives input from the temporal association cortex,
amygdala, hypothalamus, visual system, taste, olfaction
making it the highest integration center for emotional
processing.
 OFC is concerned with the appreciation of emotions of
either one’s self or of others in terms of positive or
negative reward to sensory regions.
 The medial OFC is more often activated during the
anticipation of reward, when viewing attractive faces or
when enjoying chocolate
 The lateral OFC is more activated during the absence of
reward , experiencing an unpleasant smell or touch ,
when viewing aversive pictures and when eating
chocolate to excess.

32.  A primary role of the OFC is the acquisition of appropriate
behaviors and the inhibition of inappropriate behaviors
based on reward contingencies.
 A particular feature of the OFC is suppression of
distracting internal and external signals during the
performance of current behavior
LESIONS
 OFC lesions are emotionally labile, irritable, and
impulsive.
 Overt sexual aggression is rare, sexual preoccupation
and improper sexual comments are frequent.
 May lose interest in personal appearance and hygiene,
eat excessively and show lack of concern for others &
Apathy

33.  MEDIAL PREFRONTAL CORTEX
The MPFC appears to involve analysis and appreciation of
the mental self as well as the mental status of others
 DORSOMEDIAL PREFRONTAL CORTEX (MdPFC)
Invloves in self Introspection (recollection, self-reflection,
and evaluation )
It evaluates the social situation and determines the
meaning of others’ intentions
LESION
Apathy, akinetic mutism, incontinence

34. PSYCHIATRIC SIGNIFICANCE

35. FRONTAL LOBE SYNDROME

36.  Also accompanied by ‘dysexecutive syndrome’ which
includes difficulties in
1. Formulating & setting goals
2. Developing Plans to meet goals
3. Initiating plans
4. Monitoring and correcting behaviour

37. SCHIZOPHRENIA
 Over activity of the MPFC and posterior cingulate
gyrus seen with schizophrenia at rest, suggesting
excessive introspection.
 Positive symptoms (hallucinations, delusions, and
confused thoughts) were found to correlate with
increased activity in the medial prefrontal cortex and
 Information processing in the dorsolateral pre- frontal
lobes of schizophrenic patients is deficient

38. DEPRESSION
 A significant decrease in glial density and glial
number in the OFC of patients with a history of major
depression or bipolar disorder
 Imaging studies have shown that decreased activity
in the prefrontal cortex of patients with unipolar or
bipolar depression
 Decreased left prefrontal activity on positron
emission tomography is consistently found in actively
depressed patients

39. FRONTOTEMPORAL DEMENTIA
 Also known as Pick’s disease, is a neurodegenerative
disorder.
 Histopathological findings - round aggregates of tau
protein known as Pick bodies and ubiquitinated TAR
DNA-binding protein 43 (TDP-43).
 The clinical manifestations of FTD vary depending on the
location of degeneration but often encompass prominent
personality changes, disinhibited social behavior,
aphasia, mood changes, perseveration, gluttonous
behaviour and can even be associated with motor neuron
disease.

40. BIPOLAR DISORDER
 Decreased metabolism in the DLPFC, lateral OFC,
anterior insula, and ventral striatum is seen.
OBSESSIVE-COMPULSIVE DISORDER
 Reduced volume & increased metabolism of OFC.
POSTTRAUMATIC STRESS DISORDER
 The medial prefrontal cortex has been found to be less
active in patients with PTSD in several studies
 Transcranial magnetic stimulation focused on the right
dorsolateral prefrontal cortex was reported to have a
therapeutic effect.

41. BORDERLINE PERSONALITY DISORDER
 reduced metabolism and volume reductions in BPD
patients include the orbital prefrontal cortex, cingulate
gyrus, hippocampus, and amygdala
 A decrease in metabolism seen in the DLPFC of patients
with BPD is speculated to correspond with chronic
feelings of depersonalization and unreality
AUTISM SPECTRUM DISORDERS
 A theory suggestive of MPFC involvement is seen
SEIZURES -non convulsive frontal seizure states can
produce prolonged behavioral disturbances

42. FRONTAL LOBE TUMORS :
 Behavioural changes (90%)
 Mood symptoms - anxiety, irritability, depression,
apathy, and euphoria.
 Changes in personality (40%) - irresponsibility,
disinhibition, and inappropriate sexual behavior.
 Psychotic symptoms (10%) - delusions and
hallucinations.

43. STROKE
 left middle cerebral artery stroke, would present with
right upper extremity weakness and right facial
drooping. Anterior cerebral artery strokes are
significantly less common but present with weakness
in the contralateral lower extremity.
LOBOTOMY - PSYCHOSURGERY
 Neurologist António Egas Moniz created this
procedure in early 1940s.
 It is discontinued due to severe negative effects on a
patient's personality and ability to function
independently.

44. THE END